In recent years, there has been increasing emphasis on the safe handling and disposal of toxic waste materials considered to be hazardous to the health of the general population if such materials are permitted to contaminate the atmosphere. Such safety concerns are particularly prevalent in the area of asbestos removal.
Prior to developing the invention, the inventor became aware of the need for a prefabricated structure, partially disposable, that would meet the requirements outlined in regulations issued by the Occupational Safety and Health Administration and the Environmental Protection Agency for the safe removal of hazardous wastes such as asbestos. Principal requirements for such a structure were (1) safety, (2) facility and speed in assembly, (3) flexibility with regard to the configurations which could be constructed, (4) disposability, (5) facility, speed and safety in disassembly, and (6) economy in construction and assembly.
Until now, contractors have been compelled to construct some type of enclosure at the site using lumber and plastic sheets bound together by adhesive tape, but the resulting enclosure turned out to be slow to construct, expensive to construct, and inefficient and even unsafe to use.
Environmental enclosures have existed in the prior art, but have not been suitable for use at a demolition or renovation site. Such an enclosure is disclosed in U.S. Pat. No. 4,304,224--Fortney. The enclosure disclosed in this patent is intended to provide a germ-free atmosphere or "clean room" for laboratory or research use. It is composed of a structural frame which supports a flexible transparent plastic film defining a sealed chamber or room into which air is introduced through a two-stage filter system and from which air is exhausted through a filter duct. Prior to entering the "clean room", an operator must put on a hermetically sealed suit which has a provision for receiving air from the outside and for discharging air to the exterior. The suit permits the operator to move freely within the chamber without destroying the germ-free atmosphere therein and without being contaminated by materials contained within the chamber.
Obviously, the type of enclosure disclosed in the Fortney patent is not at all suitable for use as a controlled environment system for the handling, containment and safe disposal of hazardous materials such as asbestos. Such an enclosure must be directed to the purpose of preventing exterior contamination by the contents of the enclosure, whereas the Fortney arrangement is directed to prevention of interior contamination of the enclosure by germs migrating from the exterior. In addition, the controlled environment system of concern herein must provide easy access to working personnel and their equipment, while the Fortney arrangement sacrifices easy access in favor of hermetic sealing of the enclosure via the use of sealed zippered doors. Finally, the controlled environment system of concern herein must be flexible as to the size and structure of configurations which can be constructed, and must also provide for the safe and easy disposal of hazardous materials within the enclosure once the work is completed. In contrast, the Fortney arrangement is quite standard and inflexible with regard to the configuration that can be constructed, and does not make provision for the disposal of the contents of the enclosure once work is completed (in fact, the Fortney enclosure is not discarded once the work is completed).
Two other patents, U.S. Pat. Nos. 4,059,903 and 4,108,509 of Piet et al, merely disclose a controlled environment work enclosure of small size for use in a laboratory for the handling of mercury and mercury alloys. The work enclosure of Piet et al merely comprises a hollow housing defining a small workspace with replaceable flexible plastic or rubber gloves affixed to glove rings mounted on the front of the unit to permit convenient working access to the platform contained within the unit. Thus, this arrangement is suitable for the use of hazardous materials within a laboratory, and not as a large-scale construction or demolition enclosure for the safe handling of asbestos during removal activities. Furthermore, the arrangement of Piet et al is not a disposable arrangement.
U.S. Pat. No. 4,626,291 Natale discloses a portable containment device for the treatment of hazardous materials, such as asbestos insulation. However, the Natale arrangement merely comprises a portable containment device or containment bag system having glove inserts for use in the removal of asbestos from an individual pipe section. Thus, Natale does not disclose a large-scale containment enclosure for use during demolition and large-scale asbestos removal activities.
Other patents which typify the state of the art with respect to the general technical area of concern herein include the following: 3,252,258; 3,364,642; 3,505,989; 3,561,487; 3,883,715; 4,128,966; 4,128,973; 4,163,342; 4,292,762; 4,304,068; 4,632,847; and 4,637,301.